The major task in the manufacture of sections is to provide for a high quality of products of intricate shape, as far as their surface finish and accuracy of every geometrical dimension are concerned, while at the same time providing for a high throughput of the manufacturing process.
At present, sections are predominantly manufactured by sizing in drawing and rolling mills, or else by either mechanical or chemical milling.
However, the methods of sizing products by drawing, by mechanical and chemical milling are characterized by relatively low throughput and more often than not would not provide for turning out the product of adequate quality.
The method of sizing sections by rolling is a high-throughput one; however, it is mainly used for manufacturing products of relatively simple cross-sectional shape.
The most efficient method of producing high-quality sections with sufficiently high throughput is the one of radial swaging in a specific die set in a pulsating load hydraulic press.
The concept of this method is not unlike the working in a mechanical radial-swaging machine; however, in comparison, it offers the better accuracy of the product, this accuracy being unaffected by such characteristics of the machine as the rigidity of its framework and of its effort-transmitting members and assemblies, the presence of clearances and play in the connections, etc.
The structure of a specific die set operable in pulsating load hydraulic presses is disclosed in the US Pat. No. 3,875,785 and GB Patent No. 1,396,252.
The die set includes a stationary block and a movable one, both blocks having in their end faces facing the central axis of the die set cutout portions defining inclined surfaces intersecting along a straight line parallel with the central axis of the die set. The said cutout portions accommodate a sizing die and successively arranged therewith movable and stationary knives for trimming the flanges of sections.
An advantage offered by this die set of the prior art is that it provides for sizing sections in a single pass through the die, i.e. the performance of reducing the thickness of the flanges with simultaneous trimming of their width.
However, the die set of the prior art is of a complicated structure and would not enable the sizing with simultaneous trimming of sections having four and more flanges, e.g. cross-shaped ones, or else flanges extending at different inclination angles relative to one another.